An investor believes that investing in domestic and international stocks will give a difference in the mean rate of return. They take two random samples of 15 months over the past 30 years and find the following rates of return from a selection of domestic (Group 1) and international (Group 2) investments. Can they conclude that there is a difference at the 0.10 level of significance? Assume the data is normally distributed with unequal variances. Use a confidence interval method. Round to 4 decimal places.
Average Group 1 = 2.1234, SD Group 1 = 4.8765, n1 = 15
Average Group 2 = 3.0945, SD Group 2 = 5.1115, n2 = 15
a) 1.2529 < μ1 - μ2 < 2.9831
b) 0.9700 < μ1 - μ2 < 3.4858
c) 1.1243 < μ1 - μ2 < 3.2145
d) 0.9657 < μ1 - μ2 < 3.4961
